On a low stepped circular plaza rests an open hemispheric structure of many tonnes, built of cast modular sections resting together. The four skewbacks of the horizontal circle are cabled together from a central ring. Rising arcs from these skewbacks meet at a keystone, which has a suspended plumb-bob hanging down to the centre of the ring.
The sections are cast of spent uranium, which has a density greater than lead; for this reason it is a material used for munitions, aircraft counterweights and in other industrial and medical applications. It is a highly toxic material and weakly radioactive; exposure has been linked to a variety of serious medical conditions. Consequently this piece may not be in proximity to any human contact.